Process of removing tin from phosphate liquors used in weighting silk.



serying the phosphate of soda solution and UNITED STATES BATE T OFFICE.

-ERNEST MEILI, 0F HAwTHonNE, NEW JERSEY, Ass tench To WEIDMANN SILK DYE- me 00., or PATEBSON, NEW JERSEY, A CORPORATION on NEW JERSEY.

PROCESS OF REMOVING TIN Enom PHOSPHATE LIQUORS USED'IN w IGH'riNG SILK.

No Drawing.

hemmed Ap'r. 28', 1914.

Application filed May 18, 1911. Serial No. 627,995. I

To all whom it may concern Be it known that 'I, ERNEST MEILI, a citizen of the United Statesfresidin'g at Hawthorne, in the county of Passaic and State of New Jersey, have invented a certain new and useful Process of Removing Tin from Phosphate Liquors Used in Weighting Silk, of which the following is a specification.

This invention relates to-the weighting of silk by treating it first with a solution of bichlorid of tin and then with a solution of phosphate of soda. According to the present way of weighting silk by the use of these solutions the silk, already treated with the bichloridoftin solution, is subjected tothe phosphate of soda solution, whereupon the phosphate is extracted from the silkvin any suitable way and reserved for use over again.

This process, although it involves con- 1 hence represents an economy over the older method, consisting in dipping the silk, al-

ready treated with the bichlorid of tin solution, inthe phosphate of soda solution and K then, instead of conserving the solution held by the silk, allowing it to drain ofi andreplenishing the phosphate of soda bath with fresh' solution, possesses the disadvantage that the phosphate of soda liquor has the tendency to dissolve some-of the tin oxid, so that tin phosphate accumulates more and more in the phosphate offs'oda bath the longer it is used, reducing the efiiciency thereof andhence involving a 'wasteof the materials used;

I have ascertained that the phosphate liquor, containing any amount of dissolved tin, may be chemically treated so as to effect precipitation of the tin, leaving the pure phosphate liquor free to be' drawn of!" and hence usedover again.

' In carrying out my invention the phosphate liquor, containing any amount of the dissolvedtin, is boiled with a small amount of silicate of soda, by which the tin becomes precipitated with the silicic acid, whereupon it is separated from the phosphate liquor by filtering. For example, the phosphate of soda liquor, say one thousand (1000) parts, four (4) degrees B., contain ing one (1) part of tin, or more, is boiled with four (4) parts of silicate of soda and,

upon the resultant precipitation, is filtered;- The result is a perfectly clearsolution of phosphate of soda, substantially free of tin oxid. If the phosphate of soda soLution is stronger than four i) degrees Be; the amount of silicate of soda is increased proportionately. The tin is precipitated principally as stannic acid; a small amount may be combined with phosphoricor silicic acid.

Having thus fully described my invention what I claim is:

1. The herein-described method of purifyingthe ployed in t e weighting of silk by the socalled'tinhosphate method which conhosphate of soda solution emsis'ts in ad ing to the solution a reagent." 7

which reacts on the phosphate of soda,and forms a precipitate which'carries down with it the tin in the solution.

2. The hereindescribed method of ex-' tracting tin from the phosphate of soda so-. lution employed in the Weighting ofi silk by the so-called tili pho'sphate method which consists in treating the solution with si1i-- cate of soda whereby to'precipitate the tin, and then removing the precipitate, substantially as describe 1 I .3. The herein described method of extracting tin from the phosphate of soda solution employed in the weighting of silk by the so-called tin-phosphate method which consists in treating the'solution with silicate of soda while hot, whereby to precipitate the tin, and then removing the precipitate, substantially as described.

4. A process for the regeneration of used phosphate baths employed in the weighting of silk, which consists in precipitating the tin and other metallic impurities in the bath by means of silicic acid.

5. The process for regenerating a phos-- phate bath that has been used in the weighting of silk, which consists in adding to said bath a chemical which will react with the bath to form nascent silicic acid which latter has the efiect of precipitating the Whole of the tin and ot er metallic impuri-.

ties from the bath, ass "forth.

6. A process for freeing a phosphate bath that has been used in the Weighting of silk from tin and other metallic impurities which consists in adding to said bath a soluble? silicate, and boiling the loath so treated.

7 A process for freeing a phosphate bath that has been used in the Weighting of silk,

from tin and other metallic impurities, whieh consists in addlng silicate of soda to I 

